Magnetoelectric inertia operated impact fuse for rotating projectiles



Sept 14, 1954 T. MEISTER 2,688,921

L. MAGNETOELECTRIC INERTIA OPERATED IMPACT FUSE FOR ROTATING PROJECTILES Original Filed Feb. 27, 1945 gvwe/wlo n 159 Len T.MEil5 !:e1-

i ww w Patented Sept. 14, 1954 UNITED s'mrss NT OFFICE MAGNETOELEGTRiC INERTIA OPERATED IMPACT FUSE FOR ROTATING PROJEC- TILES Leo T. Meister, Hillside, N. J.

'7 Claims.

(Grantee under Title 35, U. s. Code (1952), see. 266) The invention described herein may be manufactured and used by or for the Government for governmental purposes, without the payment to me of any royalty thereon.

This application is a division of my copending application, Serial Number 580,066, filed February 27-, 1945.

It is the chief object of the invention to provide an impact fuze for a projectile which is armed only in response to the high rotational speed imparted :by passage of the projectile through a rifled barrel.

A second object of the invention is to provide an impact fuze substantially instantaneous in operation in response to impact and hence of particular value for use in' projectiles having shaped charges.

A further object is to provide a compact magneto-electric fuze detonate-d by a squib whose firing circuit is closed only in response to high speed rotation of the projectile, and energized only in response to impact while rotating.

Other objects and advantages will become apparent from a study of the following specification in connection with the accompanying drawing, wherein:

Figure 1 is a central longitudinal cross section of one form of the fuze unarmed and Figure 2 is a corresponding cross section of a modified form of fuze, also unarmed.

Referring in detail to Figure 1, the numeral I identifies an outer fuz housing having threaded portion 2 for engagement with the trailing end of a projectile. Housing I has a central longitudinal bore 3, greatly enlarged at its end opening through the rear face of the housing, as indicated at 4. This enlarged portion is threaded at 5 to receive a threaded plug 6 having holes 1 for a spanner. As shown, when plug 6 is screwed home, its forward end has substantial clearance with the shoulder 8 between the two portions of bore 3 of different diameters. Plug 6 has a central axial bore 9 opening through its forward face only, and an annular channel Ill coaxial of bore 9 and also opening through its forward face.

Two ring-shaped sections II and I2, of insulating material have a smooth fit within channel II]. ,The contactingv faces of these rings are grooved so that they conjointly form a liquidtight toroidal chamber I3 in which a globule of mercury I4 is contained. Two diametrically opposite terminal screws I5 and I6 are threaded through the outer walls of rings II and I2 at their meeting faces and are so arranged that when the fuze is rotating at high speed, the mercury I 4 forms a ring or band electrically connecting the two, otherwise electrically insulated screws. A squib I! is fixedly positioned in central bore 9 and has firing terminals l8 and I9.

Forwardly of ring I2, channel It) carries a solenoid 2| having a smooth fit therein. The forward face of the solenoid is conveniently flush with the forward edge or face of plug 6 which seats upon an annular shoulder 22 so that, when plug I5 is turned home, shoulder 22 acts to retain rings H and I2, and solenoid 2|, firmly within channel Ill as will be evident from inspection of Figure 1. One lead 23 directly connects one terminal of solenoid 2!, with screw I5. Another lead connects the other terminal of the solehold with terminal I8 of squib I1; and a third lead 24 electrically connects squib terminal I9 with contact screw 16. Thus, the squib may be fired only when screws I5 and I6 are electrically connected by mercury I4 in response to rapid rotation and at the same time, a voltage induced in solenoid. 2|. Such a voltage is induced in response to impact of the projectile, by a ring magnet 25 which may have a central bore of the same size as bore 9. Magnet 25 has a smooth sliding fit within a counterbore in housing I. The magnet has an axially elongated slot 26 in its periphery in which fits the smooth radially inward end of a screw 21. This screw extends through a radial bore in the forward end of housing I and is held in position by its enlarged threaded outer end 21a. This construction prevents rotation of the magnet relatively to housing I. The forward edge of magnet 25 is beveled at 2511. This beveled surface is normally engaged by a number of plungers 28 fitting in corresponding radial bores in housing and urged inwardly by respective springs 29 abutting a cap 30 at their radially outward ends. This cap is threaded onto the forward reduced end of housing I and contains a booster charge 3|.

Plungers 28 thus act to urge the magnet 25 into its rearwardmost position shown but are moved radially outward to free the magnet in response to rotation of the projectile. Under this circumstance, the magnet is free to move forwardly by inertia following impact, a dis tance equal to the spacing between the magnet and shoulder 8, to thereby induce a voltage in the solenoid 2| and, when its circuit is closed through mercury M, to fire squib I'I.

The forward reduced portion of housing I has a threaded radially inwardly and rearwardly extending bore 32 opening into central aperture 3. A cup or plug 33 is threaded into bore 32. A shield or partition 34 slidably fits plug 33 and is constructed and arranged to project across and seal off aperture 3 when in the position shown. A spring 35 acts between the partition and closed outer end of plug 33, to urge the partitioninto safe position wherein squib IT is cut off from booster charge 3|. However, rotation of the projectile causes shield 34 to be moved outwardly against the thrust of spring 35 to place squib I! and charge 3| in communication. Any suitable means such as a key and keyway maybe provided to prevent rotation of shield 34 in plug 33.

The operation will be clear from the foregoing description. Prior to firing, the fuze is triply safe by reason of 1) the open circuit to squib ll, (2) the immobilization of magnet 25 by plungers 28 and (3) the cut-off efiected by partition 34. On firing, the rapid rotation causes mercury [4 to form a ring or band electrically connecting screws l4 and |5 and thus closing the circuit between solenoid 2| and squib Such rotation also moves plungers 28 and partition 34 radially outwardly so that, at the instant of impact magnet moves forwardly and effects firing of the squib as previously described, thus detonating charge 3| through the presently open passage or aperture 3 and firing the main charge, not shown.

The form of fuze shown in Figure 2 is modified by a rearrangement of the parts shown in Figure 1. In this species, a plug 36 is threaded to be screwed into the rear opening of a projectile. A cap 3'1 has a flange 31: secured to the forward face of plug 36 and houses first a booster charge 38 and, in contiguous relation a cylindrical block 39 of dielectric material having a central axial bore 40 and a circular channel 4| in its forward face. A second cylindrical block 42 of insulating material has a channel 43 in its rear face complemental to 4|, the two channels defining a closed toroidal chamber as in Figure 1, and containing a globule of mercury 44 adapted, when the projectile carrying the fuze is spinning, to form a band electrically connecting diametrically opposite contact screws 45 and 46 threaded into the chamber between the blocks.

Blocks 39 and 42 have aligned central bores to receive a solenoid 41. If desired, block 39 may be molded about the solenoid casing so that a ring of the material thereof enters an annular groove 48 in the casing and, in effect, integrally unites the block and solenoid. A ring magnet 49 is mounted for axial sliding movement in the forward portion of the bore in block 42. Rotation of the magnet relatively to block 42 is prevented by a screw 50 in a radial bore in block 42 having its smooth inner end fitting an axially elongated slot 5| in the periphery of magnet 49. Plungers 52 are mounted in radial bores in block 42 and, under urge of springs 53, engage the forward beveled edge of magnet 49 and act to hold the magnet in position contiguous to solenoid 41. The springs abut against casing 31 at their outer ends.

A squib 54 is mounted within the central aperture in solenoid 41. As in the species of Figure 1, a lead 55 connects screw 45 with one terminal of solenoid 41 whose other terminal is connected by lead 56 with squib 54. A third lead 51 connects thesquib with screw 46. The partition 58 and its mounting parts including plug 59, may be duplicates of the corresponding elements previously described in connection with Figure 1 and need not again be described. Likewise the operation of the species of Figure 2 is identical with that of Figure 1, as previously described.

Having now fully disclosed the invention, I

claim:

1. In an impact fuze for a rotating projectile, a housing having a central axis and adapted to be secured within the rear end of a projectile, dielectric means forming a toroidal chamber coaxial of said axis and having first and second diametrically opposite electrical contacts, a globule of mercury in said chamber, a squib in said housing, a solenoid fixed with said housing, a normally open circuit connecting said squib, solenoid, and contacts, and a magnet in said housing movable relatively to said solenoid by inertia in response to impact of the projectile to induce a voltage therein, said mercury forming a ring electrically connecting said contacts in response to spinning of the projectile about said central axis to thereby close said circuit.

2. In an impact fuze for a rotating projectile, a housing having a central axis and adapted to be secured within the rear end of the projectile with said axis coincident with the axis of rotation of the projectile, dielectric means forming a sealed toroidal chamber in said housing coaxial of said axis, a globule of mercury in said chamber, diametrically opposite electrical contacts in said chamber, a solenoid and ring magnet mounted in adjacent relation in said housing coaxial of said axis, a squib in said housing, a normally open circuit connecting said solenoid, squib and contacts, and means mounting said magnet for translation along said axis relatively to said solenoid in response to impact of the projectile, said mercury acting to form a ring electrically connecting said contacts and closing said circuit in response to spinning of the projectile about said axis.

3. An impact fuze for a rotating projectile comprising a housing adapted to be screwed into the rearwardly opening central aperture of a pr jectile, said housing having a central first bore, a plug threaded into said bore and having a forwardly opening second bore and a forwardlyopening annular channel coaxial of said second bore, a pair of dielectric blocks fitting said channel and having their contacting faces grooved to conjointly form a sealed toroidal chamber, first and second contacts mounted in diametrically opposite positions in said chamber, a globule of mercury in said chamber, a squib in said second bore, a solenoid in said annular channel, a ringshaped magnet mounted adjacent and forwardly of said solenoid, coaxially therewith, a booster secured to said housing at the forward end of said first bore, a partition carried by said housing and movable radially in response to centrifugal force from a first position closing said first bore between said squib and booster, to a second position clearing said first bore, and spring means urging said partition into first position.

4. A fuze as recited in claim 3, and centrifugally releasable means holding said magnet in rearwardmost position in cooperative relation with said solenoid, forward motion of said magnet on impact inducinga voltage in said solenoid.

5. In an impact fuze for spinning projectiles, a threaded plug adapted to be screwed into the rearwardly-opening recessof a projectile, a cylindrical cap secured to the forward face of said plug, a booster in said cap adjacent said plug, a block of dielectric material in said cap forwardly of said booster, said block having a central bore and forwardly-opening counterbore, a solenoid secured in said counterbore and having an open-center, a ring magnet axially movable in said counterbore adjacent and forwardly of said solenoid, there being a toroidal closed chamber in said block coaxial of said bore, a pair of diametrically opposite electrical contacts in said chamber, a globule of mercury in said chamber, a squib fixed within the open center of said solenoid, a normally open circuit connecting said solenoid, contacts and squib, said mercury forming a ring electrically connecting said contacts in response to spinning of the projectile to close said circuit and fire the squib, said magnet moving forwardly in response to impact of the projectile to induce a voltage in said solenoid.

6. In an impact fuze for a spinning projectile, a squib, a solenoid, a normally open circuit connecting said squib and solenoid, a magnet movable relatively to said solenoid to induce a voltage therein in response to momentum following impact of the projectile, and closure means for said circuit including a dielectric block having a generally toroidal chamber coaxial of the axis of spin of said projectile, first and second circumferentially-spaced contacts extending into said chamber, and a globule of electrically conducting liquid in said chamber and electrically connecting said contacts in response to centrifugal force created by spinning of the projectile to close said circuit.

7. In an impact fuze for a projectile which spins in flight, a body, dielectric means fixed with said body and having therein a toroidal chamber coaxial of the axis of spin of the projectile, first and second electrical contacts projecting into said chamber in circumferentiallyspaced relation, a quantity of mercury in said chamber, a squib, a source of voltage, and a normally-open circuit including said squib, source and contacts.

References Cited in the file of this patent UNITED STATES PATENTS Number Name 1 Date 1,776,796 Ruhlemann Sept. 30, 1930 1,955,779 Teitscheid Apr. 24, 1934 FOREIGN PATENTS Number Country Date 525,333 Great Britain Aug. 27, 1940 

